Tobacco Column Research Articles

Mathematical Modeling of Transport of Aerosol Particles in a Shredded Porous Medium

A new mathematical method is proposed to model the transport of polydisperse submicron aerosol particles in a heterogeneous porous media, and as an example, it is applied to study the transport of mainstream smoke aerosol particles in the cigarette tobacco column. The tobacco column is composed of randomly distributed pores and the aerosol particle transport is modeled utilizing a pore sub-model and taking into account aerosol particle coagulation and deposition.

Mathematical Modeling of a Lit-End Cigarette: Puffing Cycle and Effects of Puff Counts

Abstract The burning cycles of a lit-end cigarette were numerically simulated using a 3-D model that includes both the cigarette and its surrounding ambient air and the effects of buoyancy forces. The solid and gas phases were treated separately in a thermally non-equilibrium environment. The tobacco pyrolysis and char oxidation were modeled using multi-precursor models. The changes in tobacco column porosity and its subsequent effects on permeability and gas diffusivity were included. The mass, momentum, energy, and species transport equations were solved in a discretized computational domain using a commercially available computational fluid dynamics (CFD) code. The model was applied to puff a cigarette under different puffing intensities and the effects of puff volume, puff profile, and puff duration were studied. The results show that the model is capable of reproducing the major features of a burning cigarette during both smoldering and puffing. For the puffing and puff-by-puff cases, the solid and gas temperatures as well as those mainstream smoke constituents predicted by the model are in a good agreement with experimental results. A parametric study shows the significant effect of puff volume, puff profile, ventilation rate, and puff counts on solid and gas phase temperatures as well as gaseous species concentrations and mainstream smoke delivery. The buoyancy forces have shown to be very important in both smoldering and puffing.

Smoking Behavior: How Close to the Tipping Do Consumers Actually Smoke?

Abstract When smoked by the Federal Trade Commission (FTC) method, the standard butt length for filtered cigarettes is specified as tipping plus 3 mm. One of the criticisms of this standard is that the tipping overlap hides some of the tobacco column and that consumers actually smoke cigarettes past the tipping. The objective of this study was to determine how consumers actually smoke their usual brand when smoking in their everyday environment. A portable device was designed to collect and preserve cigarettes from consumers after smoking. In use, the smoldering cigarette is dropped into the device and it is closed. Upon closing, the cigarette is extinguished, the mouth end of the filter is cut and separated for further analysis, and the date and time are recorded. Fifty adult smokers per brand were recruited across 5 US cities (10 smokers/city). A wide range of brands was studied: menthol and non-menthol, 1 mg to 18 mg FTC ‘tar’ yield, 17 to 25 mm circumference, and both 85 and 100 mm lengths. A total of 10528 cigarettes from 803 subjects covering 17 brands was measured. The subjects were provided with one pack of their usual brand, as well as a collection device, and were instructed on how to use the device. The devices were collected on subsequent days. The cigarettes were then removed and the distance from the tipping to the char line was measured. The overall median butt length was tipping plus 6.7 mm with an overall average of tipping plus 8.4 mm. There was no significant effect of FTC ‘tar’ yield on either mean (p = 0.72) or median (p = 0.92) butt length.

The Influence of Cigarette Moisture to the Chemistry of Particulate Phase Smoke of a Common Commercial Cigarette

Abstract This study presents the results on the influence of cigarette moisture content to the chemical composition of particulate phase smoke. Seventy-five selected compounds were monitored for the comparison of particulate phase smoke of a commercial full-flavored (FF) cigarette with three different moisture contents at 7.8%, 14.5% and 20.4%, respectively. It was demonstrated that the smoke of a dry cigarette is richer in lower molecular mass compounds than a regular cigarette. On the other hand, the smoke of a moist cigarette is richer in higher molecular mass compounds than a regular cigarette. To maximize the influence of cigarette moisture to the chemical composition, a separate set of measurements were done using only the first three puffs of smoke. The accumulation of moisture in the tobacco column of a burning cigarette may influence the smoke composition, as generated during burning. The differences between dry, regular and moist cigarettes were more obvious for the first three puffs.

Diffusion of Moisture in a Cigarette Tobacco Column at Room Conditions

Abstract The moisture content of cigarettes has a significant impact on the shelf life and the taste of the products as well as various physical properties of cigarettes including loose ends, burning rate, hardness, and pressure drop. To prepare better products it would be helpful to develop proper mathematical models for the simulation of moisture diffusion characteristic dynamics in a cigarette. In this work, four mathematical models have been developed with appropriate assumptions adequate to analyze the dynamics of moisture diffusion in cigarettes. The simulation of the derived models was also carried out in this work. When the theoretical values produced from each model were compared with the corresponding experimental data, it was found that three models (I-II, II, III) can be used to explain the behavior of moisture in cigarettes. Convective mass transfer coefficients and effective moisture diffusivities that fit best were obtained by a regression analysis of the model using the experimental values. The simulation of the models revealed that there is no significant positional dependence of moisture content inside a tobacco column because most of the moisture dries out radially through the cigarette wrapper. The drying rate of moisture in a tobacco column is rarely affected by effective moisture diffusivity, but strongly influenced by convective mass transfer. To prevent quality deterioration of the cigarettes during long-term storage, it is concluded that improvement of the cigarette wrapper and air tightness of the package, which are directly related to the convective mass transfer, is very important.

Effect of Cigarette Variables on Ignition Propensity of Various Fabrics

A factorial matrix consisting of 25 cigarette samples, where tobacco density, circumference, paper porosity and paper citrate were varied at three levels was tested on cotton duck, treated sailcloth and four commercial fabrics. Duck fabrics are heavy canvas-type fabrics that have very high levels of potassium ions. Treated sailcloth is a light areal density fabric treated with potassium sulfate and hydroxide salts to produce ignition results that mimic those obtained with light areal density commercial fabrics. The chosen commercial fabrics had light, heavy and mid-range areal densities. The results underscore the fact that changing tobacco column parameters does not produce cigarette designs that perform consistently well on all fabric types. Lower cigarette density and reduced circumference levels reduce ignitions on duck fabrics but increase ignitions on treated sailcloth and the light areal density commercial fabric. Reducing paper porosity reduced ignitions on duck fabric, had little effect on treated sailcloth and increased ignitions on the light areal density commercial fabric. Paper citrate had the smallest effect. Ignition results on duck fabrics correlated with each other but were in contrast to those obtained with treated sailcloth. The heavy and light areal density fabrics produced similar ignition results to the duck fabrics and treated sailcloth, respectively. The two mid-weight commercial fabrics produced ignition results dissimilar to the other fabrics.

A NEW TREATMENT FOR A FILTER TIP TO DECREASE FLAVOR AND WATER MIGRATONS DURING STORAGE OF A TOBACCO PRODUCT

ABSTRACT Volatile flavors are playing an increasingly important role in the quality control of cigarettes to enhance their smoke taste and odor. The cigarettes which contain a filter tip having an activated carbon for reducing the irritant and physiological effects of the smoke are popular in the Japanese market. We found that the flavors migrate from the tobacco column to the filter tip, while spontaneously water moves backwards, depending on the adsorption equilibrium of cigarettes and its packaging.materials during storage. A new "Ethanol Adsorption Treatment" for a filter tip has been presented to decrease this undesirable flavor and water migrations. The treatment is performed by applying the binary vapor of water and ethanol to the filler tip before connecting ii with a tobacco column. Then during storage, the presence of ethanol vapor decreased the flavor migration mainly by decreasing the amounts of flavors adsorbed on the activated carbon within the filter lip. The treatment was confirmed to be effective for decreasing both flavor and water migrations simultaneously.

A New Ethanol Adsorption Treatment to Decrease Flavor and Water Migration during Storage of a Tobacco Product.

A new “Ethanol Adsorption Treatment” (EAT) for a filter has been presented to depress the migration of volatile flavor and water in a box of a tobacco product during storage and marketing. The EAT is performed by applying the binary vapor of water and ethanol to the filter tip before connecting it with a tobacco column. During the EAT, ethanol was adsorbed physically on the filter as an additive agent, and thus the water content within the filter tip was controlled to a desirable level at which the water does not migrate. Then during storage, the presence of ethanol vapor depressed the flavor migration mainly by decreasing the amounts of flavors adsorbed on the activated carbon within the filter tip. The EAT was confirmed to be effective for decreasing both the water and flavor migration simultaneously.

Cigarette characteristics, smoker characteristics, and the relationship to cigarette fires

Data were collected from eight cities on a wide range of cigarette and smoker characteristics for a sample of smokers. Of these, 564 smokers had had fires and were identified through fire department response to those fires, while the other 1,611 smokers had not had fires and were identified through a telephone sample survey of the communities. The characteristics analyzed included those that had shown evidence of a relationship to the risk of a cigarette-initiated fire, either in laboratory studies or in previous statistical analyses of fire experience. The smoker characteristics analyzed were household income, education, age, gender, and race. The cigarette characteristics analyzed were filter, tobacco column length, filter length, circumference, density, amount of tobacco, menthol, citrate, porosity, and pack type. In addition, a variable was used to control for the smoker's city. After controlling for all smoker characteristics and city, logistic regression modeling showed four cigarette characteristics to be significant: filter, filter length, porosity, and type of pack. Filter, filter length, and porosity all affect air intake, which, therefore, appears to be an important physical element in the combustion process associated with risk. Analysis limited to filtered cigarettes only showed the same characteristics to be significant, plus tobacco column length. Extension of the analysis to two-way interaction terms did not change any of the conclusions on which cigarette characteristics are important, but it did indicate that the role of pack type was different for men and women. Sensitivity analyses, shown in the appendix, supported the main conclusions that cigarette characteristics are significant after controlling for smoker characteristics and that the four specific cigarette characteristics—filter, filter length, porosity, and pack—are the ones that are significant. These analyses checked the impact of cluster sampling, sensitivity to missing data on smoker characteristics, and sensitivity to nonfire smoker cases with responses by people other than the smokers themselves. All this means that there are already cigarettes commercially available that exhibit a reduced propensity for ignition when one controls for smoker characteristics.

Effectiveness of cigarette filter tips for reducing cadmium in relation to other mainstream smoke constituents.

The effectiveness of filter tips for reducing cadmium, tar, nicotine, carbon monoxide and carbon dioxide in cigarettes was studied. The cigarettes were made from tobacco grown on municipal sewage sludge-amended soil and were therefore high in cadmium. When machine-smoked, filter tips did not result in a significant reduction of cadmium deposited on Cambridge filters. This may indicate that a considerable fraction of cadmium is present in the vapor phase of the smoke and therefore not reduced to the same extent as the tar by certain filters. Nicotine and carbon monoxide were reduced to a lesser extent than tar. This indicates that the filter tip has influenced the combustion of the tobacco column during smoking.

The Effect of Tip Dilution on the Filtration Efficiency of Upstream and Downstream Segments of Cigarette Filters

Abstract The amount of particulate matter captured by the upstream and downstream segments of ventilated filters was directly determined by a UV method. With 25 mm 3.3 dpf/35000 total denier filters the dry particulate matter efficiency of the upstream section approximately doubled and the nicotine efficiency increased by about a half in going from 0 to 70 % tip ventilation. The efficiency of the downstream segment showed only minor variations. This resulted in an increase of total filtration efficiency from 48 % to 63 % for dry particulate matter and from 40 % to 49 % for nicotine. The dry particulate matter/nicotine ratio decreased from about 15 for non-ventilated cigarettes to less than 10 at 70 % tip ventilation because the tobacco column produced smoke containing relatively more nicotine and the difference between dry particulate matter and nicotine filtration efficiencies became successively larger as ventilation increased.

Effect of Cigarette Circumference on Weight Loss during Puffs and Total Delivery of Tar and Nicotine

AbstractUsing cigarettes of different circumference but a constant packing density, the weight loss during a puff, Wp, and the total deliveries of tar and nicotine were measured. The results obtained can be summarized as follows: the puff count, n, and the weight loss during a puff, Wp, were nearly proportional to the radius of the cigarette. The total deliveries of tar and nicotine were closely proportional to the weight loss during puffs. Based on these results the following equations were derived:for tar:for nicotine:whereTNW = weight of tobacco column,L = length of tobacco column,nllµµKFrom these equations, the amount of tar and nicotine in mainstream smoke can easily be estimated.

Selected inorganic chemical composition of mainstream cigarette smoke as a function of aerodynamic particle size

Described is a new method for studying the inorganic chemical composition of various fractions of mainstream smoke separated according to particle diameter. University of Kentucky 1R1 reference cigarettes were neutron activated in a 2MW swimming pool reactor. These activated cigarettes were then smoked on a conventional reverse puffing machine and the smoke immediately diluted 200: 1 with clean air. The diluted smoke was then separated into fractions based on particle diameter in a spiral centrifuge. The separate fractions were subsequently counted on a Ge(Li) detector coupled to the proper electronics, multichannel analyzer, and dedicated computer system. Data is presented showing the relative concentration ratios of K, Na, Cl, Br and Mn. Total sulfur was assayed by long-term low-background scintillation counting. The neutron activation analyses results show that the relative ratio of Na, Cl, Br, and Mn to K remains constant regardless of size from 0.1 to 2 μm aerodynamic particle diameters. Sulfur shows a definite chemical variability compared to the other measured inorganics and is enriched in the smaller particle sizes below 0.3 μm. Total carbon was also analyzed and data is shown which compares the relative ratios of K, Na, Cl, Br, S and Mn to the total carbon content. Sulfur is enriched compared to carbon in the 0.5 μm and smaller particles. The K, Na, Cl, Br and Mn show depletions compared to carbon in both the small and large particles, but an enrichment in the 0.3–0.7 μm particles. A comparison of the inorganic ratios in dropped cigarette ash and the ionic portions of the sized mainstream smoke aerosol is presented. A possible mechanism is presented to explain how the major mass amounts of the inorganics studied are transferred to smoke. This mechanism is one of a mechanical “entrainment” of pieces of inorganic residue that during the cigarette puff, break off from the coal and are transferred into the smoke stream. The “entrained” inorganic residue is subsequently regulated in its size distribution by the normal impaction filtration mechanisms of the tobacco column. These sized “entrained” inorganics then exit in the mainstream smoke. Because the bulk of these particles is made up of the “entrained” inorganic residue, they account for the major chemical mass of the inorganics studied, while the other mechanisms of inorganic transfer (volatilization, condensation, and nuclei contributions) are shown to be of minor importance to the overall chemical transfer.

Particle Size Studies on Tobacco Smoke

AbstractTo evaluate the effects of dilution and filtration on the particle size of tobacco smoke, a cyanoacrylate fixation technique has been applied directly to smoke issuing from a cigarette. This fresh, undiluted smoke has appreciable numbers of particles with diameters less than 0.1 and relatively few particles with diameters greater than 0.5 micrometer. For a middle puff on an unfiltered tobacco cigarette, the median and mass median diameters are 0.20 and 0.32 micrometer. The experimental method involves the injection of cyanoacrylate vapor directly into the issuing smoke stream, collecting a sample of fixed particles on a membrane filter, and the use of image analysis to separate, size and count individual particles. Aging of undiluted smoke for up to 1.4 seconds essentially doubles the number and mass median diameters and decreases the particulate concentration in line with coagulation theory. Different puffs on unfiltered cigarettes have little effect on the size distribution and particulate concentration. Addition of a filter removes both larger and smaller particles, and tends to skew the distribution to smaller sizes. The reduction in particulate concentration in filtered smoke is as expected from nicotine removal efficiencies. Filter dilution tends to skew the size distribution to larger sizes, while tobacco column dilution has no great effect. Particulate concentration correlates well with overall dilution levels.

The use of pressure drop measurements for estimating ventilation and paper porosity/Verwendung von Zugwiderstandsmesswerten zur Abschätzung von Ventilation und Papierporosität

AbstractIn our recent article on the above-mentioned topic, the derivation of the pressure drop equations was based on the first approximation that diluting air flow is constant over the length of a filter or tobacco column. While this is a reasonable approximation for filters and tobacco columns with low levels of dilution, it appears to give inaccurate results for tobacco columns with high levels of dilution, as was pointed out by Cummings.

The Use of Pressure Drop Measurements for Estimating Ventilation and Paper Porosity

Abstract Equations for calculating dilutions in vented cigarette filters and tobacco columns from pressure drop measurements are derived. These calculated dilutions are found to agree closely with those directly measured for a variety of commercial and experimental cigarettes wrapped with perforated and porous tipping and with different cigarette papers. The effect of hole placement on dilution and cigarette pressure is estimated. The effects of filter dilution on particulate matter, condensate and carbon monoxide delivery are discussed. A method for measuring filter dilution during smoking by means of pressure drop measurements is outlined and results for a typical vented filter cigarette are shown and discussed. The use of pressure drop measurements for estimating paper porosity and amount of dilution in the tobacco column on finished cigarettes is out-lined. The dilution obtained by this method was generally higher compared to the results found by a model based on a capillary flow regime, which suggests that flow through ordinary cigarette paper is a combination of capillary and orifice flow. The non-destructive nature and simplicity of pressure drop measurements make this method of measuring dilution useful in quality control of cigarette production.

Cigarette Smoke Formation Studies: IV. The Dynamic Measurement of the AxiaI Density of a Burning Cigarette

AbstractMuch research has gone into establishing the temperature gradients that exist inside a burning cigarette. These temperature gradients should correspond to changes in the density of the tobacco column due to the condensation and subsequent re-evaporation of volatiles resulting from pyrolysis, combustion, and final ash formation. These dynamic measurements on the burning cigarette were made using a modified beta thickness gauge. A beam of collimated beta particles from a

Wool Cigarette Filters Part Ill: Selective Removal of Volatile Components with Polyethylenlmlne-Quaternary Ammonium Mixtures

AbstractChemical and biological assays showed that wool filters containing mixtures of commercially available polyethylenimines (PEI) and quaternary ammonium compounds (QUAT) selectively removed proportions of the biologically active volatile constituents of cigarette smoke. The action of the QUAT was synergistic in that it enhanced the performance of PEI filters but, alone, was ineffective in retaining volatile components. Only water-soluble QUATs with one long hydrocarbon chain (> 10 C-atoms) attached to nitrogen were effective. The best removal efficiencies were obtained with a PEI/QUAT ratio in the range 0.8-1.0 and 5-10 % by weight of each additive on the filter material. Analyses of puffs at stages along the tobacco column indicated that the treated filters retained their effectiveness from the first to the last puffs. The treated filters significantly increased the pH of the mainstream smoke.